Periods

I’ve had my period since I’m 11 years old. I am now 26. My period has always been normal and always on time but since last year my period has been coming like every other month or so and is extremely painful. My last period was in April and I still haven’t gotten a period yet but the last couple of days my back has been hurting so bad so I know my period is getting ready to come. I haven’t been to the guy now yet so I’m just wondering if this is definitely something I should be worried about also I am not sexually active. I haven’t been sexually active in like two years